Fontforge Python module — is sue in drawing in character uni00B5

I'm having issues lately with some extended characters using Fontforge Python extension.
I've reduced to the minimum code to reproduce the issue which is the following: 

import fontforge
import random
font = fontforge.font()
font.encoding = "UnicodeBmp"
caracter = 'uni00B5'
font.createMappedChar(caracter).unicode
pen = font[caracter].glyphPen()


The result is the following error:

  File "min.py", line 8, in <module>
    pen = font[caracter].glyphPen()
TypeError: No such glyph

Any idea if is a Fontforge issue or if I have to use another encoding? 
Thank you,

Dimitre
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